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12v battery problem and stranded!

simplesolar

Member
Jun 30, 2013
250
5
SoCal
I think my 12v battery is dead like others on the forum. Car shut down at an intersection and now I am stuck in the middle of no where. Suck :( waiting for tow truck.
 

JPP

Active Member
Feb 4, 2013
3,056
1,284
SF Bay Area, CA
...I have now placed an old set of jumper cables into the trunk storage area, so that if I have the dreaded 12V failure I can pop the nosecone, get a jump and maybe limp home.
 

Sparrow

S105/ Roadster 189
Dec 14, 2010
755
242
Marietta, GA
My 12 volt battery failed a week ago and the car was undriveable, but I was still able to open doors and frunk and the interior lights still came on. I measured the voltage at 11.5 volts at the time. This failure occurred one week after the battery had been replaced proactively. The fix was to replace the DC/DC converter.
 

JPP

Active Member
Feb 4, 2013
3,056
1,284
SF Bay Area, CA
And how do you pop the trunk with failed 12V?

Crawl into the trunk if necessary (flipping the rear seats down as appropriate) to get to the storage well. Note that I do not keep them in the frunk (though could use the mechanical release uner the passenger dash). The nosecone comes out without opening the frunk.
 

ChadS

Last tank of gas: March 2009
Jul 16, 2009
3,323
2,674
Redmond, WA
A few months ago I took my car in to get the storage cubby installed, and asked about the 12V issue. I was told some cars had issues, but mine was not on the list so it should be fine.

Last week I took my car back in for its 1-year service check...and this time they told me that they were going to give me a new 12V "just in case". (I have never had a problem) So their response to the issue has changed...it is still unclear to me whether the problem is the battery, the DC/DC converter, the firmware that decides when to charge the 12V, vampire drains, etc. Most likely it is a combination.

I did have a problem in the Roadster once. There were similar issues there, and after a couple of years my 12V battery got too weak to unlock the car (fortunately the top was off so I could just reach in and open them, and the car did start). Tesla gave me a new 12V battery under warranty. Then a couple of months later, they called me and told me they wanted to give me ANOTHER 12V battery, because the one they gave me wasn't good enough.
 

Smop

Banned
May 23, 2013
65
2
California
I am not sold on the 12v batteries Tesla is using. I know there are a few lithium ion 12v batteries out there but they are probably very expensive. I have been through a few 12v batteries on my Model S. I recently got the 12v battery low warning again and recently replaced the battery with an Odyssey 900 CCA 12v battery. I have ran these batteries for years in heavy duty applications and they have never let me down. We will see if it works out with the Model S but I would rather spend a few hundred and fix the problem permanently than have to deal with this problem again.

The original 1.5 roadster actually used a part of the main pack to power the 12v accessories. I think some law was enacted though that forced car manufacturers to have a separate 12v battery, so that was changed in subsequent models.
 

Red

Member
Sep 27, 2013
34
0
earth
Check the voltage with which the battery is "charged" by the DC DC.
It should be above 13.5v or over 13.8 at least. If not, it is not the
battery that is faulty. If it is undercharged, especially to low 12v ish
or below, it will sulphate very quickly and become unusable.

If it undercharges, they need to replace or fix the DC DC unit.

In meantime, you can mitigate it by having a 12v battery charger charge the battery
every time you charge the car at home or somewhere where you have a 110v or 220v
plug. But that is not a solution. Just to get by.

I am not sold on the 12v batteries Tesla is using. I know there are a few lithium ion 12v batteries out there but they are probably very expensive. I have been through a few 12v batteries on my Model S. I recently got the 12v battery low warning again and recently replaced the battery with an Odyssey 900 CCA 12v battery. I have ran these batteries for years in heavy duty applications and they have never let me down. We will see if it works out with the Model S but I would rather spend a few hundred and fix the problem permanently than have to deal with this problem again.

The original 1.5 roadster actually used a part of the main pack to power the 12v accessories. I think some law was enacted though that forced car manufacturers to have a separate 12v battery, so that was changed in subsequent models.
 

Mayhemm

Model S P85+ "Lola"
Nov 9, 2012
1,966
32
Saskatchewan, Canada
I recently got the 12v battery low warning again and recently replaced the battery with an Odyssey 900 CCA 12v battery. I have ran these batteries for years in heavy duty applications and they have never let me down. We will see if it works out with the Model S but I would rather spend a few hundred and fix the problem permanently than have to deal with this problem again.

I'm curious as to how you found a compatible aftermarket battery? I've heard Model S batteries are quite involved and difficult to access as well (the battery itself, not the terminals exposed by removing the nosecone)
 

Smop

Banned
May 23, 2013
65
2
California
Check the voltage with which the battery is "charged" by the DC DC.
It should be above 13.5v or over 13.8 at least. If not, it is not the
battery that is faulty. If it is undercharged, especially to low 12v ish
or below, it will sulphate very quickly and become unusable.

If it undercharges, they need to replace or fix the DC DC unit.

In meantime, you can mitigate it by having a 12v battery charger charge the battery
every time you charge the car at home or somewhere where you have a 110v or 220v
plug. But that is not a solution. Just to get by.

I have had my DC-DC replaced as well. The issue was definitely a failed 12v. Under load the CCAs would drop to 185 and 11.8v.

I'm curious as to how you found a compatible aftermarket battery? I've heard Model S batteries are quite involved and difficult to access as well (the battery itself, not the terminals exposed by removing the nosecone)

Requires partial disassembly of the frunk. Battery is located by the passenger side windshield cowl. Not that difficult. I pulled the battery, took it to my local odyssey dealer and we matched a battery that would work.

WP_20130911_002_zpsdabc378f.jpg
 

wycolo

Active Member
May 16, 2012
3,068
423
WA & WY
And how do you pop the trunk with failed 12V? [MK]

Hatch has no mechanical release found so far. I hope there actually IS one!

MS 12v battery is (roughly) equivalent to UB12350 - 12v 35AmpereHour U-1 AGM (absorbent Glass Mat) Lead Terminal $95.00 in lots of six. Sold by Battery Systems located in major cities. Available 'at all times' since it is a standard wheelchair battery. The UB12350 is 'deep cycle' whereas the latest MS battery reportedly is 'kinda deep cycle'.
--
 

islandbayy

Active Member
Feb 25, 2013
2,650
1,024
Greendale, Wisconsin
And how do you pop the trunk with failed 12V? [MK]

Hatch has no mechanical release found so far. I hope there actually IS one!

MS 12v battery is (roughly) equivalent to UB12350 - 12v 35AmpereHour U-1 AGM (absorbent Glass Mat) Lead Terminal $95.00 in lots of six. Sold by Battery Systems located in major cities. Available 'at all times' since it is a standard wheelchair battery. The UB12350 is 'deep cycle' whereas the latest MS battery reportedly is 'kinda deep cycle'.
--


 
Last edited by a moderator:

Tommy

Member
Mar 3, 2010
882
3
The great OC
@SMOP can you provide us the group # of the Odyssey battery; better yet the particular Odyssey battery you used. Mileage wise, I will be out of warranty this time next year and I too don't mind spending a bit more to get a good quality battery to avoid having battery related problems.
 

Smop

Banned
May 23, 2013
65
2
California
@SMOP can you provide us the group # of the Odyssey battery; better yet the particular Odyssey battery you used. Mileage wise, I will be out of warranty this time next year and I too don't mind spending a bit more to get a good quality battery to avoid having battery related problems.

I want to say a group 75 battery but I honestly don't remember.
 

wycolo

Active Member
May 16, 2012
3,068
423
WA & WY
>I want to say a group 75 battery [Smop]

The U-1 (form factor) battery I listed has POS on left NEG on right. MS is reversed: U1R. Also the posts are made to accept a vertical bolt that ties several cables to the POS terminal. U1R is only available NON-AGM at the present time according to Battery Systems, so there is liquid acid inside (no glass matting) but this should not be significant. But they are deep cycle!

If you install remote terminals inside the Frunk then you can quickly connect a U1 battery into the 12 volt system should you find reason to do so. Or any other 12v battery for that matter.



>And how do you pop the trunk with failed 12V? [MK]

@islandbayy: The video you reposted does not answer this question assuming 'trunk' to mean HATCH.

Ok, I levered off the plastic cover and my MS does have the manual release cable to open Hatch. Pry yours off a few times to make it easier to do. This in a car with NO 3rd seats. Problem solved, thanx!
--
 
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